This invention relates generally to apparatuses for physically placing electronic devices in position for being tested by electronic testing equipment, and more specifically to apparatuses commonly known as handlers.
In this specification, the terms "electronic devices" and "devices" shall include all manufactured items capable of being tested by electronic means through a contactor, such as integrated circuits, transistors, diodes, hybird circuits, and the like. As used in this specification, a "handler" includes any apparatus that physically places one or more electronic devices in position for testing by electronic testing equipment to which the handler is interfaced. The interface between the electronic testing equipment and any electronic devices in position for testing is through one or more contactors.
Electronic devices are normally manufactured to specifications which set forth their parametric and functional characteristics over a range of temperatures. In order to insure that the devices meet the specification, they must be tested electronically. Testing is done by either selecting random samples from lots or by testing 100% of each lot.
In the past 10 years, electronic devices particularily integrated circuits have become extremely complex. For instance in the last 7 years memory devices have gone from less than 1000 bytes per device to over 64,000 bytes per device. Such complexity has required very thorough testing. In order to have a reliable product, some manufacturers, as a rule, test 100% of their more complex devices.
The proliferation of computers and computer peripherals in recent years has significantly increased the demand for electronic devices. In order to meet this demand, more devices must be manufactured and more devices must be tested. Thus, the increased complexity of the electronic devices, the need for reliability, and the increased demand for electronic devices have placed a heavy burden on those responsible for testing the devices.
Handlers were developed to aid in the testing of the electronic devices. A well designed handler usually comprises five major components. Electronic devices are usually transported in carriers such as tubes, so the first component is a means of moving the devices from the tubes and dispersing the devices into the second component of the handler, an environmental of thermal storage chamber. The storage chamber conditions the devices to an elevated temperature, typically 125.degree., or to a depressed temperature, typically -55.degree.. From the storage chamber the devices are singularized and moved to the third component of the handler, a mechanism which plugs the device into a contactor for testing. After the device is tested, the device moves to the fourth component of the handler, a category sorter which sorts the devices into categorized compartments according to the test results. The fifth component of the handler is, of course, the control circuitry and the means by which the handler interfaces to the operator.
A contactor is a device that has electrical leads that close and open upon the leads of the device under test. During the time the leads are closed, the electronic test equipment is usually performing a variety of electrical tests.
Heretofore, most handlers had only the capability of presenting one device for testing at a time. Such handlers were capable of handling the volume of devices as long as the test time for a device was on the order of 200 milliseconds. As "dynamic random access memory" devices became popular (for instance the 16K RAM) the throughput of the handlers was significantly reduced because test times became very long (approximately 10-20 seconds as compared to 200 milliseconds for a common device). To increase the throughput, dual handlers were introduced. The dual handlers typically feed two devices from the storage into a mechanism which plugs the two devices into two contactors. The two devices are tested and then exited by means of a single exit track. The dual handler, however, has the disadvantage of having one device positioned above the other device in a single track system. If the upper device in a single track has failed, it cannot be sorted past the lower device in the track. Thus, a bad device that is detected early in testing, cannot be replaced by an untested device until the device below it has completed its test.
Some manufacturers have introduced systems whereby two tracks and four contactors are used but such systems have the same disadvantage as dual systems in that a bad device cannot circumvent the other devices being tested.
This invention presents a single track system, that is, a single track feeds the devices from the storage into the mechanism which plugs the devices into the contactors, and a single track receives the devices from the mechanism and disperses them into the catagory sorter. However, in this invention, a plurality of devices may be tested in parallel and, during testing each device can be sorted and replaced independent of the others. With this invention, a plurality of devices may be tested in stages. All devices can be run through a quick test to determine if they meet certain specifications and, if any fail, they can be rejected and replaced with new devices without disturbing the devices which passed the initial test. Thus, while some devices are being rejected, others can be undergoing testing. Such a system has heretofore not been presented.
Other advantages and attributes of this invention will become readily apparent upon a reading of the text hereinafter.